The lithium-ion battery that didn’t explode

By | September 18, 2018

The lithium-ion battery that didn’t explode

Batteries are our lifeblood. Lithium-ion power cells, first commercialized by Sony in 1991, enable nearly every 21st century convenience: Phones, laptops, wireless headphones, cordless power tools — even electric vehicles.

But like the other great conveniences of our modern age — automobiles and air travel — on the rare occasions lithium batteries go wrong, they can go catastrophically wrong.

Just ask the family of Nazrin Hassan, the Malaysian tech incubator CEO who died after one of his phones burst into flame. Consider Tallmadge D’Elia, who expired when his exploding vape pen sent fragments into his skull. Or think of the hoverboard owners who watched their houses burn down.

chappaqua-fd-hoverboard-swagway-full.jpg
A New York man filed a lawsuit after his Swagway hoverboard exploded while charging.

Chappaqua Fire Department

You’re far more likely to be struck by lightning (1 in 1,042,000) than ever see a battery flame up (1 in 10 million is the number experts tend to quote). But the fact remains: Like your car’s gasoline engine, lithium-ion batteries require flammable liquids to generate their power in a controlled chemical reaction.

If that reaction gets out of control because the battery’s structural integrity is breached — or if there’s a widespread manufacturing defect like one that afflicted 2016’s Samsung’s Galaxy Note 7 — all bets are off. That’s why, even as we surround ourselves with more lithium-ion-powered devices, we don’t fully trust them yet.

But what if that fraction of a doubt could be removed? What if the safety profile of lithium-ion batteries could be made to be so reliable that even a catastrophic structural failure — up to and including being pierced by a bullet — wouldn’t cause them to explode?

That’s exactly the promise of SafeCore, by a company called Amionx. The tiny California firm claims it’s created a lithium-ion battery that won’t catch fire even if crushed, shot or otherwise breached.

CNET flew to Amionx’s Carlsbad facilities earlier this year, where we submitted SafeCore batteries — and some normal lithium-ion competitors — to a full range of torture tests.

Spoiler alert: When we stabbed, shot and smashed the “brand X” batteries, they burst into beautiful, brilliant, scary flame. But under identical conditions, the SafeCore batteries didn’t catch fire.

According to Amionx, the company’s breakthrough isn’t just a battery that doesn’t easily combust. It’s that the company’s scientists discovered a formula they claim could easily be applied to existing battery manufacturing lines — no new machines required — to bring this breakthrough to any lithium-ion battery in the world.

They claim the invention could take those batteries places they’ve never been safe enough to go before.

How? Amionx has a secret sauce. Literally.

The invention

A palm-tree laden Carlsbad business park just past Legoland California may not be where you’d think to find the next leap in battery safety. But walk through a special door past the normal business trappings — the vacant receptionist’s desk, the cubicles and conference rooms — and you step onto a miniature factory floor with its own lithium-ion battery assembly line.

The company says these machines can produce a million lithium-ion battery cells per year, and they’re not just here for show: American Lithium Energy, the parent company of Amionx with which it shares the building, supplies batteries to the US military for use in heavy-duty trucks and lightly armored vehicles like the MRAP, among other projects. (Public records show the company has received $2.77 million in R&D grants from the Army to date.)

Today, the humming machines are being used to show what Amionx’s secret sauce can do. One spoonful at a time, a technician drizzles the black goop onto a thin sheet of metal winding through the machine from reel to giant reel. This particular apparatus is an electrode laminator, which coats the battery’s all-important positive and negative terminals in an array of chemicals before they get sliced into smaller pieces and stacked (or wound) into a complete battery cell.

What we’re seeing seems to be a typical, ordinary battery making process, goop and all — but Amionx’s compound is a special formula that took four years to create.

When a battery heats up, threatening to catch fire, Amionx’s special material acts like an electrical fuse, creating a physical gap between two key components of the battery. That gap means electricity is forced to take a far more difficult path through the cell, which dramatically slows down the reaction to the point a battery doesn’t get hot enough to catch fire or explode.

It’s not like there aren’t other ways to protect a battery. Amionx founder and CTO Dr. Jiang Fan admits that today’s lithium-ion batteries have a variety of other mechanisms that can prevent fires, including current interrupters, shutdown separators and PTC (positive temperature coefficient) devices, but he says all of them can fail — a battery can heat up so fast that some safety mechanisms may literally melt before they can take action.

“That’s why sometimes even though they have the shutdown separator for 20 years, they still have these thermal incidents,” says Fan — adding that his SafeCore kicks in right away.

The test

To test out Amionx’s safety promise, we open another door at the back of the factory floor, and walk outside into a fenced area of the building’s parking lot — where industrial-strength battery crushing and puncturing test chambers are waiting to let the smoke out of these cells. One machine is designed to drop a huge, heavy weight onto a metal bar laid flat across the top of the battery, completely crushing a large portion of a battery in an instant, while the other slowly punctures it with a giant nail.

While our camera crew takes a moment to set up a super-slow-motion shot, I quietly crouch down next to a pile of ready-to-test batteries and whip out my multimeter to verify the current. But sure enough, the meter reads 4.2 volts — we’re looking at fully charged lithium-ions.

Then, we play NASA Mission Control, counting down to the moment our technician will press the big button and these batteries will get their chance to ignite.

First, we try a standard lithium-ion pouch battery pack — no SafeCore material inside. As the nail goes in, it’s astounding how quickly the battery reacts. It bulges like a balloon, bursts with a puff of smoke, shoots out flying reddish sparks and finally explodes into a huge column of flame that reaches the ceiling of the test chamber — all within 6 seconds flat.

With the crushing machine, the same reaction takes just 3 seconds. (Dr. Fan says that’s because the wider crush zone means we’re shorting out the battery more thoroughly.)

But when we place SafeCore-treated batteries in the same torture devices, there’s no bulge, no smoke, no flame. The punctured, crushed batteries are warm, maybe even hot to the touch for the next 10 minutes, but they feel no more dangerous than the hand warmers my Scoutmaster used to hand out on Boy Scout camping trips.

A couple of hours later, we test the company’s most extreme claim at the Pala Shooting Range, located on the Pala Indian Reservation some 30 miles northeast of Amionx HQ. With a short, sharp crack, an expert rifleman puts a .223 round through each battery with precision — just after our camera crew lines up their shot and scrambles to safety.

 

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